Question 216764
A bacteria population doubles every four minutes. If the population begins with one cell, how long will it take to grow to 1,024 cells? 
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1024 is 2^10, so there must be 10 doublings.
10*4 = 40 minutes.
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Call 4 minutes the period:
P  #
----
0  1
1  2
2  4
3  8
4  16
5  32
6  64
7  128
8  256
9  512
10 1024
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1024 is commonly called 1K, as in computer memory (K is for kilo). 
1K = 1024 bits or bytes.
1 Meg = 1,048,576 = 2^20
1 Gig = 1,073,741,824 = 2^30
1 Tera = a lot, I think it's 10^40
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Another approach to the problem (remember the problem?) is:
log(1024)/log(2) = 10 = # of periods
We divide by the log of 2 because in each period the # is multiplied by 2.  If the bacteria tripled each period, we would divide by log of 3, etc.